2009 Radiology Exam - Spec Proced/NM Case 1

Half of the cases for the Special Procedures/Nuclear Medicine section of the exam were presented in electronic form and half were presented in film based form or by video fluoroscopy.

CASE 1: This case was presented as a film based study.

• 1 yr, neutered male, Shih Tzu
• Insidious onset of progressive bilateral hind limb weakness.
• Bilateral negative conscious proprioception and 2+ patellar-cranial tibial reflexes.

See images below. Click to enlarge.

OBSERVATIONS:

Survey films: No abnormalities.

Myelogram:

• The spinal needle is positioned ventrally at L5/6 subarachnoid space.
• There is excellent distribution of the contrast through the lumbar and thoracic regions.
• Beginning at caudal end of T7 is a focal accumulation of contrast in a dilated section of the dorsal subarachnoid space.
• It forms a sharply marginated caudally convex cavity that occupies the majority of the right to left width of cord and approximately 90% of the dorsal-ventral thickness of the cord at its largest dimensions.
• It tapers in all dimensions from mid-T7 cranially to resume normal dorsal subarachnoid space dimension at caudal T4.
• No other abnormalities evident.

SYNTHESIS:

• Focal dilation of the dorsal subarachnoid space from T4 through T7 with greatest accumulation and severe compression of the spinal cord through T7.
• Primary differential diagnosis is a spinal arachnoid cyst.

MANAGEMENT:
Cross-sectional imaging could improve the determination of the degree of spinal cord compression and more accurately determine of the length of involvement. With the contrast present CT would be appropriate.

FOLLOW-UP:
The myelogram was followed by a CT which confirmed the location and showed a “U-shaped” compression of the spinal cord. The patient was treated by dorsal laminectomy and fenestration of the cyst. No short or long term follow up was available.

CANDIDATE PERFORMANCE:
Candidates generally did very well on the overall assessment of this case.